AP Chemistry · Fall 2024 CED

Unit 1 — Atomic Structure and Properties

Line-by-line lessons · one lesson per atom: 63 atom-lessons and 5 gates, in teaching order. Each lesson reveals one idea per Continue; checks take over the screen. Pick any lesson, or start at lesson 1. Draft segments update as final content lands.

The Mole Bridge

Counting by weighingHow many water molecules are in this glass? You can't count them — but you can weigh them.
1Why we need molesAST-001 · 6 checks · generated2Avogadro's numberAST-002 · 6 checks · generated3Relative particle mass and molar massAST-003 · 6 checks · generated
Mole calculationsTwo conversions, both directions: mass ↔ moles ↔ particles.
4Find moles from massAST-004 · 6 checks · final5Find mass from molesAST-005 · 6 checks · generated6Find particle count from molesAST-006 · 6 checks · generated7Find moles from particle countAST-007 · 6 checks · generated
Mole chain — capstone lessonsMulti-step chains, cold — no intermediate prompts.
8Chain mass ↔ moles ↔ particlesAST-008 · capstone · 6 checks · generated
GATEGate · Mole chaincheckpoint · 8 cold items

Instruments Meet Atoms

Reading mass spectraA real chlorine mass spectrum — why two peaks for one element?
9Isotopes and mass numberAST-008A · 6 checks · generated10Read a mass spectrumAST-009 · 6 checks · generated11Percent abundance from peak heightsAST-009A · 6 checks · generated12Calculate average atomic massAST-010 · 6 checks · generated13Work backward from average atomic massAST-011 · 6 checks · generated
Classifying matterParticulate diagrams — which of these are pure?
14Molecules vs formula unitsAST-012 · 6 checks · generated15Pure substance or mixture?AST-013 · 6 checks · generated16Same compound, same mass ratioAST-014 · 6 checks · generated
From masses to formulasUse a compound's formula and measured mass ratios to move from percent composition to an empirical formula.
17Calculate percent composition by massAST-015 · 6 checks · generated18What is an empirical formula?AST-016 · 6 checks · generated19Find the empirical formulaAST-017 · 6 checks · generated
Composition — capstone lessonsPurity judgment and mixture composition, cold.
20Judge purity from elemental analysisAST-018 · capstone · 6 checks · generated21Composition of a mixtureAST-019 · capstone · 6 checks · generated
GATEGate · Compositioncheckpoint · 13 cold items

Inside the Atom

Structure and the master forceOne law explains most of this course.
22What an atom is made ofAST-020 · 6 checks · generated23Force and distance between chargesAST-020A · 6 checks · generated24Force and charge sizeAST-020B · 6 checks · generated25Coulomb's lawAST-021 · 6 checks · generated26Compare electrostatic forces with Coulomb's lawAST-022 · 6 checks · generated
Where electrons liveWhy does sodium always lose exactly one electron?
27Shells and subshellsAST-023 · 6 checks · generated28Core electrons vs valence electronsAST-024 · 6 checks · generated29The Aufbau principleAST-025 · 6 checks · generated30Subshell capacities: s holds 2, p holds 6AST-025A · 6 checks · generated31Write a ground-state electron configuration (atom)AST-026 · 6 checks · generated32Noble-gas core shorthandAST-026A · 6 checks · generated33Write a ground-state electron configuration (ion)AST-027 · 6 checks · generated
Shielding and ZeffBoth electrons feel an 11+ nucleus — why is one hundreds of times easier to remove?
34Effective nuclear charge and shieldingAST-028 · 6 checks · generated35Which electron is easier to remove?AST-029 · 6 checks · generated
Seeing shells: PESA real PES spectrum — the closest thing to a picture of electron shells chemistry has.
36Read a PES spectrumAST-030 · 6 checks · generated37Predict a PES spectrum from configurationAST-031 · 6 checks · generated38Check a PES spectrum against a proposed structureAST-032 · 6 checks · generated
Atomic structure — capstone lessonsElement ID from a full PES spectrum, plus the Coulombic why.
39Identify an element from its PES spectrumAST-033 · capstone · 6 checks · generated40Explain PES peak energies CoulombicallyAST-034 · capstone · 6 checks · generated
GATEGate · Atomic structurecheckpoint · 19 cold items

The Table's Logic

The table's schema · Ionization energyThe periodic table is a database — here's its schema.
41The periodic table encodes electron configurationAST-035 · 6 checks · generated42What is ionization energy?AST-036 · 6 checks · generated43Ionization energy generally increases across a periodAST-037 · 6 checks · generated44Ionization energy increases up a groupAST-038 · 6 checks · generated45Rank ionization energyAST-039 · 6 checks · generated46The two dips in the ionization-energy trendAST-039A · 6 checks · generated
Atomic and ionic radiusAcross, up, and the trick case: isoelectronic series.
47Atomic radius decreases across a periodAST-040 · 6 checks · generated48Atomic and ionic radius decreases up a groupAST-041 · 6 checks · generated49Isoelectronic species: more protons, smaller radiusAST-042 · 6 checks · generated50Rank atomic and ionic radiusAST-043 · 6 checks · generated
Electron affinitySame machine, new property: what happens when an atom gains an electron.
51What is electron affinity?AST-044 · 6 checks · generated52Electron affinity: broad across-period tendency and interruptionsAST-045 · 6 checks · generated53Electron affinity within specified groupsAST-046 · 6 checks · generated54Rank electron affinityAST-047 · 6 checks · generated
ElectronegativityThe tug-of-war inside every bond — which atom pulls harder?
55What is electronegativity?AST-048 · 6 checks · generated56Electronegativity increases across a periodAST-049 · 6 checks · generated57Electronegativity increases up a groupAST-050 · 6 checks · generated58Rank electronegativityAST-051 · 6 checks · generated
Trends — capstone lessonsEstimate an unmeasured property; explain why.
59Estimate an unmeasured propertyAST-052 · capstone · 6 checks · generated
GATEGate · Trendscheckpoint · 19 cold items

Toward Compounds

Why atoms bondSodium explodes in water; neon does nothing. Same row. Why?
60Will two elements bond, and how?AST-053 · 6 checks · generated61Same column, analogous compoundAST-054 · 6 checks · generated62Predict an ion's typical chargeAST-055 · 6 checks · generated63Write the formula from the ion chargesAST-055A · 6 checks · generated
GATEGate · Unit 1checkpoint · 10 cold items